1. Field of Invention
The present invention relates, generally, to a golf club head and, more specifically, to a golf club head with enhanced deformation for hitting a golf ball farther.
2. Discussion of the Background
When a golf club strikes a golf ball at rest, the ball is propelled at high speed from the tee to the landing area. Thus, the kinetic energy of the moving club head is converted to kinetic energy in the moving golf ball. The golf ball is only in contact with the face of the golf club for a few millionths of a second during impact and the distance achieved by the golf ball is a result of the combination of the initial velocity of the ball after impact, the launch angle, and the spin of the ball. Generally, however, the greater the velocity of the ball after impact, the farther the ball will travel.
The mass of the club head and the velocity at impact combine to determine the initial velocity of the golf ball after impact. However, not all of the energy transferred to the ball is converted to kinetic energy and manifested as velocity. Some of the energy manifests as heat in the ball. Much of the kinetic energy lost as heat is related to the viscoelastic response of the ball during deformation.
The present invention is, in part, a result of the discovery that a golf club face that deforms in preference to the ball will, unless it is a lossy viscoelastomer, generally have a smaller hysteresis loop on deformation and, therefore, result in less energy loss. In addition, it has been found that it is preferable that the face of the club head deform more than the remainder of the club head body. Thus, controlling deformation of the golf club head in preference to deformation of the golf ball will result in the golf ball traveling farther.
Generally, a golf club comprises a shaft portion, a head portion, and a grip portion. The part of the golf club head portion that comprises the hitting surface is referred to as the golf club xe2x80x9cfacexe2x80x9d. Generally, a golf club face abuts or is adjacent to both a top wall (or crown) of the club head and a bottom wall (or sole) of the club head.
Most xe2x80x9cwoodsxe2x80x9d, such as the driver and the fairway woods, are in the form of a hollow shell (or perhaps filled with foam), usually of metal. Because only the best and strongest golfers can effectively swing a driver head that weighs more than 220 grams, the maximum weight of the club head is essentially a design constraint of the club head. Further, when the front side of the face of the golf club head strikes a golf ball, extremely large impact forces are produced potentially causing cracking and/or material failure. Thus, the golf club face portion must be structurally adequate to withstand large repeated forces, such as those associated with ball impact. In addition, a large club head face is highly desirable because it strongly reduces the percentage of errant hits.
Thus, there are contrasting design considerations when designing a golf club headxe2x80x94the desirability of a light club head, but with a large club face and a club head that is durable enough to withstand repeated striking of the ball. One method of increasing the durability of the club head is to add additional material (e.g., steel or titanium) to thicken the club face or to add ribs to the club face. However, the designer cannot simply add additional material to strengthen the face indiscriminately because doing so also increases the overall weight of the club head, which is undesirable.
Prior golf club heads typically had relatively thick faces, which would deform only slightly at impact thereby causing the golf ball to deform, which created a significant loss of kinetic energy through conversion of heat in the ball. Also, at impact, most faces vibrate at a fundamental frequency of 4,000 to 5,000 Hertz. The present invention results in significantly greater deformation of the club face at impact and a higher fundamental frequency of about 6,000 Hertz at impact. The result is a significantly lower deformation of the ball resulting in less loss of energy through heat conversion in the ball and consequently a higher initial velocity at impact, resulting in greater distance of ball flight.
Thus, there is a need for a new golf club head with a club face structure providing enhanced deformation for improving club performance, and that has structural integrity, thereby reducing cracking and material failure, without otherwise adversely affecting club performance, look, and feel; and with limited affect on club head weight.
The primary object of the present invention is to overcome the deficiencies of the prior art described above by providing a golf club head with enhanced deformation for hitting a golf ball farther.
Another key object of the present invention is to provide a golf club head that imparts more kinetic energy to the golf ball than existing club heads.
Another key object of the present invention is to provide a golf club head that reduces the amount of energy that is converted to heat in the ball when striking the ball.
Still another key object of the present invention is to provide a golf club head having a club face that has portions that are thin enough to permit enhanced deformation and that are durable enough to avoid structural failure from repeated use.
Yet another object of the present invention is to provide a club head with enhanced deformation that results in the golf ball traveling farther, that is achieved without exceeding a preferred club head weight.
Still another object of the present invention is to provide a golf club head having a higher fundamental frequency than comparable existing club heads.
The present invention accomplishes these objects and others by providing a golf club head having a cast sole and a crown joined seamlessly as one piece with an opening for a face plate to be fitted into the body, and the face plate fabricated from sheet metal, precision cut by, for example, a laser and precision formed in a die under extremely high pressure. The face plate includes a lower portion and an upper portion. The sole and crown part of the body are cast thinner than most other club heads to promote deformation when striking a golf ball. A parabolic shaped rise in both the crown and sole provide increased lateral strength while aiding in reducing the deformation of the ball at impact. The lower portion of the face has two end portions and a center portion with the end portions having a first thickness. The center portion and the upper portion of the face have a second thickness that is thicker than the first thickness. In addition, the face plate is welded or bonded into a front opening of the cast body. The overall effect of this invention is to reduce deformation of the golf ball at impact, which reduces the energy lost as heat in the golf ball, resulting in farther drives.